This new 5-day version of those fasting diets was an attempt to achieve the same benefits without going to extremes, Longo explains. He adds, "It was designed to try to eliminate the burden of chronic diets and interventions, and be something that most people could actually do."
MORE: 5 Safe Ways To Try A Fasting DietThe Research
The latest study (after lots of earlier work in animals) split healthy adults into two groups. Five days a month, one group stuck to a restricted-calorie diet provided by the researchers. It included foods like vegetable-based soups, energy bars, energy drinks, snacks, chamomile tea, and vegetable supplement tablets—all of which totaled between 750 and 1, 100 daily calories. The dieters ate normally the other 25 days of the month and stuck to their usual exercise routines. The second group was told to follow their typical diet and workout habits.
The study was small, Longo says, but the results were promising. At the end of 3 months, the dieters lost an average of 3% of their body weight (up to 14 pounds), and their lean muscle mass increased. Compared with the nondieters, the diet group also enjoyed lower blood glucose levels, lower levels of insulin-like growth factors (which drive the aging process), and less inflammation.
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Is It Safe?
Not for everyone, Longo says. There are definitely people for whom the diet could be dangerous, including anyone with a history of anorexia, anyone taking diabetes drugs, or pregnant women. Even if you're not one of those people, Longo says the diet was designed to be done under the supervision of a doctor or registered dietician. It includes a specific number of calories that deliver key nutrients, all of which are needed for the diet to be safe and effective. So PLEASE, don't try to mimic these results with your own 750-calorie-a-day plan.
What Can I Do?
Longo says by year's end, a commercial diet program based on his research should be available. In the meantime, you can ask your doctor about fasting diets, or read more about the forthcoming program built on Longo and USC's research. Eventually, Longo says he hopes intermittent fasting diets could be used to treat diabetes and cardiovascular disease, though that would require FDA approval and is still likely years in the future.